Photographic developer



r Patented Oct. 13, 1936 umTsosTATE's PATENT OFFICE aosun rn orocnarmc mivnmrm Hermann Schnltes,

Mainz-Momb aoh, Germany 'assignor to Dentsche Goldand Silber-Scheide: anstalt, vormals Roessler, .Franktort-on-th Main, Germany, a company of Germany v No Drawing. Application January 10, 1936 Serial No. 58.541

3 Claims. (CI. 95-88) less hydroquinone is objectionable in so far as it requires a relatively great amount of time to perform the development of latent photographs. After the course of this longer period of time the development occurs too-hardly. This fact on the other hand is very disadvantageous for the production of true photographs. Furthermore hydroquinone imparts to the photographs a faded yellowish colour.

0n the other hand pyrogallol monoalkyl ether itself produces soft photographs within a relatively short period of time, an eiiect, which is often undesirable. It was suggested to use combinations consisting of hydroquinone and p-methylg5 amino-phenol as developers. These mixtures however, are objectionable as they have an aggressive and dyeing effect upon the skin. The developers according to the present invention are free from these disadvantages, 'in spite of the fact that pyrogallol, itself produces a skin dyeing The present invention avoids the above mentioned disadvantages. When using hydroquinone in admixture with e. g. pyrogalloi monomethyl ether, a developer is obtained which enables the development of the photograph to be performed within an exceedingly short period of time. During this period of time the development proceeds gradually so as to obtain photos which are absolutely true to the original, without the production of undesirable yellowish colours.

According to the present invention hydro-- quinone may be used in combinationv with any pyrogallol monoalkyl ether or homologues thereof. Mixtures of these pyrogallol compounds may likewise be used. Good results are obtained-by using mixtures of hydroquinone with pyrogallol monomethyl ether or in an analogous manner' and hydroquinone in the ratio of. say 1:1. Mixtures with a greater amount of hydroquinone (e. g. twice that of the weight of pyrogallol monomethyl ether) yield excellent results.

Other developers known per se e. g. p-methyl- 5 amino-phenol may be admixed to the above described mixtures.

For the purpose of giving those versed in the art a better understanding of the invention, the following specific and illustrative exampies are given: 9

Example 1 Example 2 The following developer which is suited for de- 26 veloping negatives consists of z 100 parts by weight of water, 7.2 g. sodium sulflte (NarSOr'IHzO) 3.6 g. sodium carbonate, 0.07 g. sodium bromide 80 and 0.6 g. of a mixture'consisting of methyl pyrogallol monomethyl ether and hydroquinone in the proportion of 1:2.

. Example 3 Instead of the above described mixtures of hydroquinone and pyrogallol compounds the following mixture may be likewise used: 1.5 parts by weight of pyrogallol monomethyl ether, 1.5 parts 7 by weight of hydroquinone, 0.5 part by weight of o p-methylamino-phenol sulfate (so called Metoi") In spite of the fact that the above mentioned pyrogallol compounds as well as hydroquinone are effective developers, it could not be foreseen 5 that mixtures of both offer properties surpassing by far the efliciency of the components.

I claim:-

1. A photographic developer containing pyrogallol monoalkyl ether together with hydroqui- 5o DORE;

2. A photographic developer-containing monomethyl ether of pyrogallol together with hydroquinone.

3. A photographic developer containing monomethyl ether of methyl pyrogallol together with hydroquinone. HERMANN SOHULTES. 

